There are a variety of medical conditions in which the heart cannot pump sufficient blood to meet the body's normal requirements for nutrients and oxygen. Congestive heart failure is one condition in which the heart cannot pump enough blood to meet the needs of the body's other organs. Cardiac output can be too low for a variety of reasons, including coronary artery disease, endocarditis and myocarditis, diabetes, obesity, past heart attacks, high blood pressure, congenital defects, valve disease, or thyroid disease, to name a few. Where cardiac output falls, blood returning to the heart through veins can accumulate before the heart, causing fluid accumulation in the tissues. When cardiac output is too low, the body may take compensatory action including retention of salt by the kidneys. In response to salt retention, the body may retain greater quantities of water to balance sodium, and excess fluids can escape from the circulatory system causing edema (swelling) in other parts of the body. Edema is one of many complications arising from reduced cardiac output and congestive heart failure. The present invention is useful in treating edema, congestive heart failure and reduced cardiac output. Coronary artery disease is another condition that results in insufficient quantities of blood being pumped. Angina pectoris is a condition resulting from coronary artery disease. The present invention is useful in treating both coronary artery disease and angina pectoris.
There have been various devices in the prior art to treat patients through the use of non-invasive units and pulsation, but they are limited in their mechanical operation, precision of operation, stimulation of blood flow, and have failed to address concerns of the present invention.
External counterpulsation developed as a means of treating reduced cardiac output and circulatory disorder stemming from disease. Counterpulsation treatment involves the application of pressure, usually from distal to proximal portions of a patient's extremities, where such application is synchronized with heart rhythms. The treatment augments blood pressure, typically increasing pressure during the diastolic phase of the heart, as such treatment is known to relieve and treat medical conditions associated with reduced cardiac output. Clarence Dennis described an early hydraulic external counterpulsation device and method of its use in U.S. Pat. No. 3,303,841 (Feb. 14, 1967). Dr. Cohen, in American Cardiovascular Journal (30(10) 656–661, 1973) described another device for counterpulsation that made use of balloons which would sequentially inflate and deflate around the limbs of a patient to augment blood pressure. Similar devices using balloons have been described in Chinese patents CN 85200905 (U.S. Pat. No. 4,753,226); Chinese patents CN 88203328, and CN 1057189A.
A series of Zheng patents, including U.S. Pat. No. 4,753,226 (Jun. 28, 1988), U.S. Pat. No. 5,554,103 (Sep. 10, 1996), and U.S. Pat. No. 5,997,540 (Dec. 7, 1999) disclose counterpulsation devices employing sequential inflation of balloon cuffs around the extremities, wherein cuffs are inflated by fluid. All three Zheng patents disclose an external counterpulsation device where a series of air bladders are positioned within a rigid or semi-rigid cuff around the legs. The bladders are sequentially inflated and deflated with fluid, such that blood pressure is augmented in the patient. The Zheng '103 and Zheng '540 patents provide for cooled fluid and for monitoring of blood pressure and blood oxygen saturation; however, both retain a similar mechanism dependent on compression of fluid such as air or water. The Zheng '540 modifies the shape of the air bladder and cuffs, but retains a similar mechanism requiring rapid fluid distribution, influx and efflux through balloons in the cuffs.
Deficiencies with the prior counterpulsation cuffs include the requirement of a relatively heavy and noisy compressor and fluid reservoirs for inflating and deflating the cuffs; a lack of portability due to the size and weight of the apparatus; and the need for more than a 120 volt current. There are deficiencies with regard to patients being bounced up and down while subjected to the treatment. Additionally, because the prior art requires circuitous movement of fluid through the apparatus, there is a consequent lack of ability to manipulate action of the cuffs with a high degree of precision. Moreover, as the cuff returns only to an original position of contact with the patient's skin, blood-flow through the cuffed extremity is not fully encouraged.